Total Knee Arthroplasty System and Method

ABSTRACT

Disclosed herein are prosthesis, surgical tools, and methods to preserve one or more ligaments of the knee by cutting a least a portion of natural bone during joint surgery. The natural bone may be cut using various methods and associated cutting guides, and the natural bone is retained along with the natural attachment of an associated soft tissue structure. The bone block cutting guides may create a variety of standard natural block shapes or may create mechanical mating features (e.g., keystone or dovetail configuration) in the natural bone portion that may be inserted, wedged, press-fit, and/or mechanically attached to the tibia. The natural bone block with the associated soft tissue may be further secured by incorporating features in the tibial prosthesis, providing the surgeon with additional fixation components and/or fixation mechanisms.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/640,703 entitled “Total Knee Arthroplasty Systemand Method,” filed Apr. 30, 2012, and U.S. Provisional PatentApplication Ser. No. 61/781,626 entitled “Total Knee Arthroplasty Systemand Method,” filed Mar. 14, 2013. The disclosure of these documents isincorporated by reference in their entireties.

TECHNICAL FIELD

The invention relates to improved orthopedic implants, as well asrelated methods, designs, systems and models. More specifically,disclosed herein are improved methods, designs and/or systems for jointimplant components that facilitate retention and/or repair of connectiveand/or soft tissues during a joint replacement procedure, includingpreservation of the anterior cruciate ligament (ACL).

BACKGROUND OF THE INVENTION

When a patient's knee is severely damaged, such as by osteoarthritis,rheumatoid arthritis, or post-traumatic arthritis, it may be desirous torepair and/or replace portions or the entirety of the knee with a totalor partial knee replacement implant. Knee replacement surgery, alsoknown as knee arthroplasty, can help relieve pain and restore functionin injured and/or severely diseased knee joints, and is a well-toleratedand highly successful procedure. Where a total joint replacement isneeded, it is often performed by a surgeon via an open procedure.

In an open procedure, the surgeon typically begins by making an incisionthrough the various skin, fascia, and muscle layers to expose the kneejoint and laterally dislocating the patella. The anterior cruciateligament is often excised (if not already damaged or severed), and thesurgeon will selectively sever or leave intact the posterior cruciateligament—depending on the surgeon's preference and the condition of thePCL. Next, various surgical techniques are used to ablate, remove, shapeor otherwise prepare the arthritic joint surfaces, and the tibia andfemur are exposed for preparation and resection to accept variousimplant components.

It is well known in the art that knee arthroplasty involves the removalof one or more of the ligaments connecting the femur and the tibia.Often the normal function of one or more of the ligaments is severelycompromised due to the deterioration or injury of the knee joint. One ofthe main purposes of a knee implant is to recreate the normal functionof these removed ligaments. During this process, the ACL is almostalways resected unless the surgeon chooses to use both a medial andlateral uni-compartment replacement. Meanwhile, the posterior cruciateligament (PCL) is preserved in only about half of knee replacementsperformed.

Once the underlying bony anatomical support structures have beenprepared, both the tibia and femur will typically receive an artificialjoint component made of metal alloys, high-grade plastics and/orpolymers to replace native anatomy and desirably function as a new kneejoint. In the case of tibial implant components, the artificial jointcan include a metal receiver tray that is firmly fixed to the tibia. Inmany cases, the tibial implant further includes a medical grade plasticinsert (i.e. it may also be known as a “spacer” or “liner”) that can beattached to the tray and positioned between the femoral component(s) andthe tibial tray to create a smooth gliding surface for articulation ofthe components. Such a system can also allow for inserts of multiplesizes and/or thicknesses, which facilitates in-situ balancing of theknee as well as allowing the placement of inserts of differing designsand/or shapes.

Various surgical procedures in the past have sought to retain connectiveknee tissues during joint repair and/or replacement, but such techniquesand associated implant designs have not gained widespread clinicalacceptance for a variety of reasons. See, for example, U.S. Pat. No.4,207,627 to Cloutier, entitled “Knee Prosthesis” filed Jun. 17, 1980,and J. M. Cloutier, Results of Total Knee Arthroplasty With ANon-Constrained Prosthesis, 65 J. BONE JOINT SURG. AM. 906 (1983); J. M.Cloutier et al., Total Knee Arthroplasty with Retention of Both CruciateLigaments: A Nine to Eleven-Year Follow-Up Study, 81-A J. BONE JOINTSURG. AM. 697 (May 1999); Nowakowski A M, et al. Investigating theprimary stability of the transversal support tibial plateau concept toretain both cruciate ligaments during total knee arthroplasty. J ApplBiomater Biomech. 2012 March 30:0; and Ries, M D, Effect of ACLsacrifice, retention, or substitution on kinematics after TKA.Orthopedics. 2007 Aug.; 30 (8 Suppl):74-6.

While the implantation of total knee implant components via openprocedures is a well-accepted procedure that is well tolerated bypatients and has a high success rate, surgeons often prefer to minimizethe disruption and/or removal of hard and soft tissues except whereabsolutely necessary. For example, the use of minimally-invasive and/orless-invasive surgical procedures has become increasingly prevalent, assuch procedures are often associated with faster patient healing timesand less scarification of the patient's anatomy. Moreover, whereportions of a patient's existing anatomy, such as an ACL or PCL, aresubstantially intact and/or functional in the damaged knee, manysurgeons would prefer to maintain the integrity of these structuresduring the surgical implantation procedure, as such structures cangreatly contribute to the ultimate stability and/or performance of thetreated anatomy. Unfortunately, many current implant designs require theremoval of such structures, even where such structures are fullyfunctional, in order to accommodate the implant components.

BRIEF SUMMARY OF THE INVENTION

There is a need in the art for joint replacement implant components,tools and associated procedures that facilitate the retention and/orrepair of anatomical structures such as the ACL and/or PCL (and/or otherrelevant hard and/or soft tissue structures) during knee arthroplastyprocedures.

It is an object of various exemplary embodiments of the presentinvention to overcome at least some of the disadvantages mentioned aboveassociated with prior art devices and surgical procedures. The presentinvention provides an improved knee replacement system comprising noveltibial prostheses, novel bone-cutting instruments, and improved surgicaltechniques and methods for knee arthroplasty. The present invention isan improvement over the prior art because it allows for the preservationof the anterior cruciate ligament (ACL) and/or posterior cruciateligament (PCL) in a total knee arthroplasty. In various embodiments, theACL attachment remains affixed to a native tibial bone block, which canimprove the normal kinematics of the knee joint.

The various embodiments described herein include implant componentssuitable for use in a patient's knee, including multi-component systemsincorporating tibial trays, inserts, tools, methods, techniques andvarious devices that facilitate the preservation and/or repair of theACL and PCL of a patient. Preservation of the ACL and/or PCL of apatient may improve physiological function and/or motion of the knee.Various other embodiments enable the retention of anatomical structuresthat can facilitate the surgical repair of various hard and/or softtissues, including connective tissues such as the ACL and/or PCL of apatient. The joint replacement implant may be a standard implant, amodular implant and/or a patient-specific or adapted implant, includingpatient-specific implants and surgical tools created using preoperativeimage data of the patient's anatomy.

In various exemplary embodiments, a special bone block forming tool,also referenced as a bone block cutting guide, is provided to remove andshape a bone block from the tibial spine. The bone block forming toolmay separate a portion of the tibial bone that includes the ACLinsertion from other portions of the tibia. The bone block and attachedACL may be repositioned and/or otherwise moved aside to allow thesurgeon free access to the tibia and/or femur to prepare the relevantbones to receive implant components. Once the femoral and/or tibialimplant components have been implanted, the bone block and attached ACLcan be reattached to the tibia (and/or attached to the tibial component,if desired and/or necessary) and/or could be repositioned in a notch orother feature of the tibial implant such that the ACL and attached boneblock regain some or all of their function in stabilizing the knee. Invarious alternative embodiments, if the surgeon did not like how the ACLreconstruction turned out and wished to employ a standard total kneearthroscopy implant and associated surgical procedures, the bone blockcould be removed and the ACL transected, allowing for the insertion ofthe standard components.

In various embodiments, the implant components can include features suchas cutout sections, notches or “windows” for accommodating variousportions of the patient's natural anatomy, including bony anatomicalstructures and/or soft tissue structures. Desirably, a cutout can act asan anchoring site for the bone block and attached ACL and/or PCL afterimplant insertion. In various embodiments, cutouts can also facilitatethe positioning and/or anchoring of a tibial implant prosthesis to theunderlying anatomical structures. In addition, various embodiments oftools and procedures described herein facilitate the preparation of thepatient's anatomical structures for the implant components.

In various embodiments, the inventions described herein include systemshaving ligament retaining components and associated surgical techniques,including tibial or femoral component systems, guides, tools andsurgical techniques. The inventions described herein may be successfullyapplied to other damaged or diseased articulating joints, or opposingjoint structures (i.e., creation of bone blocks and associatedconnective tissue anchoring locations on one or both opposing surfacesof a joint, such as the tibia and/or femur, where appropriate) includingprocedures where a surgeon desires to preserve natural ligaments and/orother underlying anatomical structures. Such joints can include variousother joints of a body, e.g., ankle, foot, elbow, hand, wrist, shoulder,hip, spine or other joints. Also, various embodiments described hereincan be successfully applied to total knee, bicompartmental orunicompartmental knee surgery.

In various embodiments described herein, the surgeon may use thesurgical tools described herein to remove a section of bone with the ACLattached (“bone block”), and dislocate the bone block to facilitate theuse of guide tools, jigs and/or surgical tools to expose and preparesurfaces of the tibia, which can be more easily accommodated andperformed when the tibia has been subluxed relative to the femur. Ifdesired, the various implants, tools, and procedures described hereinfacilitate the employment of ligament repair and/or replacementprocedures, including the restoration of natural or artificial ACLand/or PCL structures, after the various joint replacement and/orresurfacing procedures described herein have been accomplished.

In various alternative embodiments, it may be desirous that the surgeonalternatively and/or additionally removes portions of the ACL from thefemur, and in such cases an exemplary femoral implant, tibial implant,and/or surgical cutting tools could be provided that includes featuresfor creating and reattaching a femoral or tibial bone block to theimplant component in a manner similar to that described herein inconnection with the tibia.

Disclosed herein are various advanced methods, devices, systems forimplants, tools and techniques that facilitate the surgical repair of aknee joint while allowing retention, repair and/or replacement of thenatural ligaments of the knee (and/or other related structures), therebydesirably preserving controlled rotation and translation of the repairedjoint. In many embodiments, the procedures can provide adequate painrelief, preserve normal axial alignment of the limb, and preservestability.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other objects, aspects, features, and advantages ofembodiments will become more apparent and may be better understood byreferring to the following description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a perspective view of a knee joint, showing associatedhard tissue structures and soft connective tissues;

FIG. 2 depicts a frontal view of the femur and tibia bones of the kneejoint of FIG. 1;

FIG. 3A depicts a frontal view of a tibia including a set of exemplaryresection surfaces;

FIG. 3B depicts a top view of a tibia illustrating a common location ofthe ACL and PCL;

FIGS. 4A and 4B depict one exemplary embodiment of a bone block cuttingguide;

FIGS. 4C through 4E depict an alternative embodiment of the bone blockcutting guide of FIG. 4A;

FIG. 5A depicts one alternative embodiment of a bone block cutting orforming tool;

FIGS. 5B through 5D depict additional alternative embodiments of a bonecutting block;

FIGS. 6A and 6B depicts alternative embodiments of a bone block formingtool;

FIG. 7A depicts an additional alternative embodiment of a square-shapedbone block forming tool;

FIGS. 7B and 7C depicts additional alternative embodiments of awedged-shaped bone block forming tool;

FIGS. 8A and 8B depicts one exemplary embodiment of a tibial prosthesis;

FIGS. 9 and 10 depict alternative embodiments of a tibial prosthesis;

FIGS. 11A and 11B depict another alternative embodiment of a tibialprosthesis;

FIGS. 12A and 12B depicts exemplary embodiments of a tibial prosthesisthat may have medial/lateral integrated features to allow securing ofthe bone block with a plurality of sutures;

FIGS. 13A and 13B depicts exemplary embodiments of a tibial prosthesisthat may have anterior/posterior integrated features to allow securingof the bone block with a plurality of sutures;

FIGS. 14A and 14B depicts exemplary embodiments of a tibial prosthesisthat may have medial/lateral integrated features to allow securing ofthe bone block with a plurality of sutures and securing arm;

FIGS. 15A and 15B depicts a tibial prosthesis of FIG. 14A placed on aresected tibia and a bone block with the ACL reattached to tibia using aplurality of sutures;

FIGS. 16A and 16B depicts a tibial prosthesis of FIG. 12A placed on aresected tibia and a bone block with the ACL reattached to tibia using aplurality of sutures and securing arm;

FIGS. 17A and 17B depicts a tibial prosthesis of FIG. 13A placed on aresected tibia and a bone block with the ACL reattached to tibia using aplurality of sutures and securing arm;

FIG. 18 depicts an embodiment of a wedge shaped bone forming tool andits corresponding cut to form a wedge shaped bone block; and

FIG. 19 depicts a lateral view of one embodiment of a bone blockreattached to the tibia.

DETAILED DESCRIPTION OF THE INVENTION

Ligament Preservation

The various embodiments described herein may facilitate the retention ofboth the PCL and ACL, which can significantly impact the surgicalprocedure in a variety of ways. For example, where an ACL is sacrificed,damaged or is otherwise deemed unnecessary, the removal of suchstructure often improves the ability of the surgeon to access the tibialand/or femoral surfaces. When the ACL is severed or otherwise released,the tibia can be advanced some distance anterior relative to the femur,which allows the surgeon to dislocate the knee to some degree and gainbetter access to the upper surface of the tibia from a more cephaladorientation. In a similar manner, severing or release of the PCL canfacilitate some degree of advancement of the femur relative to thetibia. In contrast, when the femur and tibia are retain its connectiontogether via the flexible structures of the ACL and PCL, the healthy ACLand PCL cooperate to allow the femur to rotate relative to the tibia (ina known manner and relationship), the ligaments further cooperate tolimit relative motion between the tibia and femur in ananterior/posterior direction for stability and alignment, and/or asurgeon's direct access to the upper surface of the tibia may be limitedto the anterior face of the tibia with some limited access space betweenthe articulating surfaces of the femur and tibia. As a result, it isadvantageous to create implants, tools and techniques that may obtainthe advantages of ligament retention and ligament release during theknee surgery.

Accordingly, various embodiments described herein facilitate thesurgical repair and/or replacement of tibial and/or femoral articulatingsurfaces and associated structures via a less-invasive and/or minimallyinvasive approach. In addition, various embodiments described herein canbe utilized with equal utility in open surgical procedures where the ACLand/or PCL have been retained (bicruciate bone blocks) as describedherein.

FIG. 1 depicts a perspective view of a knee joint, showing a femur 5, atibia 10, a patella 15 and a fibula 20. A number of connectivestructures extend between the various bones and/or other structures ofthe knee, including the patellar tendon 25, the medial collateralligament 30 (MCL), the lateral collateral ligament 35 (LCL), theposterior cruciate ligament 40 (PCL) and the anterior cruciate ligament45 (ACL). Also shown is the meniscus 50, which is depicted between thefemur 5 and the tibia 10.

FIG. 2 depicts a frontal view of the femur 5 and tibia 10 of the kneejoint of FIG. 1, the tibial surface including a medial surface 60, alateral surface 55 and a central region 65 (not shown) which includes amedial intercondylar tubercle 75 and a lateral intercondylar tubercle70.

FIG. 3A depicts a frontal view of a tibia 10 including a series ofresection surfaces A, B, C and D. Traditionally, in a total knee jointreplacement procedure a single planar resection of the entire tibia isperformed, thereby creating a flat planar surface for placement oftibial components (not shown). Alternatively, a resection of one or moreportions of the tibia (areas B and/or D) could be accomplished toaccommodate unicoldylar and/or bicondylar replacement/resurfacing ofindividual articulating surfaces of the tibia. In various embodimentsdescribed herein, preparation of the tibial surface can include removalof material from multiple regions of the tibia, including B, D and someor all portions of C. If desired, the depth of the various tibialresections can be varied, and can include depths less than, equal to orgreater than those shown (i.e., A, B, C and/or D) on the figure. Invarious embodiments, an upper portion of the surface of the tibia can beresected using any of the described bone cutting tools herein, where theanterior portion (section C) of the upper portion (which includes theinsertion point of the ACL) may be separated from the remainder of theupper portion, a tibial implant is secured to the now exposed resectedsurface of the tibia, and the anterior portion including the insertionpoint of the ACL is returned and secured to the tibial implant and/ortibia, thereby restoring the function of the ACL to the surgicallyrepaired knee. FIG. 18 shows an anterior-posterior view of exemplaryresection cuts where one embodiment of a bone block may be cut andreattached to the tibia. (do we need an AP view showing tibial implanton top of cut surface of tibia with ACL bone block reattached to tibia?)

FIG. 3B depicts the top view of a tibia 10 illustrating the location ofthe ACL 67 and the PCL 65. In some embodiments, the surgeon may wish topreoperatively determine if the patient qualifies for this ligamentpreservation technique, verify the location of the ligaments, and/orassess the measurements of the ligaments and respective bone 72, and/ormake surgical tool selections to make a final decision whether topreserve the ACL and/or PCL during the surgery. The surgeon may employ aseries of preoperative images or scans during a patient's pre-operativerange of motion, such as pre-operative flexion contracture,pre-operative extension lag, pre-operative ligament balancing,pre-operative ligament tension, and/or pre-operative coronal alignment,and then assess these results and compare them to the overall combinedthickness of the intended prosthesis (femoral component, polyethylenecomponent, and tibial component) to assist with the determination. Oncethe surgeon has made this determination, the surgeon may proceed toorder, acquire or custom design the various tools and/or its componentsfrom the manufacturer that are necessary for surgery by analyzing thepreoperative data. Alternatively, a minimally invasive procedure orother arthroscopic procedures on the patient's knee or other anatomicalstructure could be conducted to preoperatively determine whether the ACLand/or PCL is torn and/or sufficiently stable to proceed withpreservation.

Bone Block Tools

In various embodiments of the present invention, a special bone blockforming tool (also referenced as a bone block cutting guide—BBCG) can beprovided to shape a bone block from the tibial spine. As seen in FIG.3B, the ACL 67 may be positioned anteriorly and centered with one end ofthe ACL 67 attached to the tibial bone 10. Similarly, the PCL 65 may bepositioned posteriorly and centered with one end attached to the tibialbone 10. Using preoperative images and data or other acceptable methodsknown in the art, the surgeon may select the proper bone block cuttingguide to cut an optimal portion of bone from the proximal tibia 72, withthe block remaining connected to the ACL 67. The bone block forming toolmay be designed with a specific and/or a desired bone block shape thatcan accommodate a currently available tibial prosthesis design or acustom designed tibial prosthesis.

In various embodiments, the bone block may have a substantiallyrectangular shape, with a size that is approximately 5-10 millimeterswide, 5-10 mm thick, and 10-15 mm long. Of course, other shapes may beobtained, depending upon the shape of cutting tools (i.e., square,wedge, dove-tailed shaped, curved) and/or the surgeon's preference. Thebone block size may also vary, depending upon the surgeon's preferenceor patient's anatomy. A patient specific bone block could be made tomaximize the healing of the bone block back to the proximal tibia andminimize the chance of a bone block fracture or non-union (during and/orafter surgery).

In various embodiments, the surgical tools (i.e. bone block formingtools or bone block cutting guides) for cutting the bone block may beformed in a fully integrated, one-piece design or could be modular withone or more pieces provided that assist the surgeon with placement,removal, and/or adaptation of the bone block guide and/or tools withother tools, jigs or instruments commonly used during knee surgery orother joint surgeries.

FIGS. 4A and 4B depict one embodiment of a bone block cutting guide 100that can guide a reciprocating saw blade to make two sidewall cuts. Thebone block cutting guide 100 includes at least two walls 110 and atleast two slots 120 that can accommodate a blade of a reciprocating sawor similar surgical tools. The bone block cutting guide 100 may includea channel 112 that may be sized, matched, and/or conform to thedimensions of the ligament that will be preserved. The bone blockcutting guide 100 may be designed with a small hook 130 or other featurethat can be attached to the saw guides 110, where the hook is sized tofit the dimension of the ACL or appropriate ligament when the saw guideis in a desired position. The hook 130 may be placed in variouspositions on the bone block cutting guide. The hook 130 may bepositioned in a similar plane of the slots 120 to allow for cutting theblock on the articular tibial surface, the hook 130 may be placed in anoffset plane of the slots 120 (as shown in FIG. 4B) or the hook 130 maybe positioned in a perpendicular plane (not shown) of the slots 120 toallow for cutting the block on the anterior surface of the tibia. Thehook may also be an integrated piece or a modular piece. In use, thehook 130 is placed around the ACL insertion on the tibia with the ACLapproximately centered in the block and the block may be placed on thearticular tibial surface (a non-resected surface), which desirablyensures that the ACL insertion point is centered prior to cutting orremoving a portion of the tibial bone. The ACL may naturally lie in thechannel 112 of the bone block cutting guide 100 during cutting. Thesurgeon may then use a simple osteotome and/or reciprocating saw to cutthe posterior portion of the bone block. If desired, the surgeon mayfirst make a standard horizontal proximal tibial bone cut (as shown inFIG. 3A, section A). A thin metal shim or plate could slide into thishorizontal saw cut to protect the tibial plateau bone from thereciprocating saw blade as it cut down through the slot 120.

The slots 120 may be designed to determine the overall size of thedesired bone block. The slots may be configured to a desired height 115,width 125 and depth 135. These dimensions may be obtained frompreoperative images of the patients' anatomy, or the manufacturer maydecide to use a database library to provide several standard sizes tomanufacture the bone cutting guide 100. These slots could be parallel orconverge to a point such that a horizontal cut would be unnecessary.

FIGS. 4C and 4D depict additional views of the bone cutting guide 100 ofFIG. 4B. FIG. 4E depicts one alternative embodiment of the bone cuttingguide with an associated handle 140. The handle may be integrated withinthe bone cutting guide 100 or the handle 140 may be modular for easyremoval and attachment and/or storage in a surgical kit.

FIG. 5A depicts one alternative embodiment of a bone block cutting guide150 which includes an upper section 155 and a lower section 160. Theupper section includes a hook 165 which sized to fit the dimension of anACL when the bone block cutting guide 150 is in a desired position. Thelower section 160 includes a rectangular box or cutter 170 having anedged or cutting surface on an upper edge, which can be formed in anyshape, including a rounded, curved, wedged and/or rectangular blockshape. The rectangular box or cutter 170 may have various sharpenedsurfaces, such as tapered blade edges, serrated edges, compound (double)bevels, chisels, chisel with back bevel, asymmetrical semi-convex,and/or any combination thereof. The rectangular box or cutter 170 may bemodular or integrated within the lower section 160 of the bone blockcutting guide 150. The upper and lower sections 155 and 160 aredesirably connected by a compression connection or other arrangement,which in FIG. 5A is depicted as a 4-bar linkage 175. Alternatively, thecompression connection may be any mechanism known in the art to allow orprovide a compression connection between the two pieces. The upper andlower sections 155 and 160 desirably can be compressed together by thesurgeon.

In use, the surgeon first would perform the standard proximal tibialbone cut at a depth that would allow for the implantation of the tibialcomponents. The tibial bone from the articular side would be elevatedfrom the non-articular tibial bone with a broad osteotome or similarinstrument a great enough distance to allow the width 152 of the lowersection 160 (see FIG. 5A) of the bone block cutting guide. The normalACL attachment to the tibial spine (see section C in FIG. 3A) on thearticular side of the tibial bone would be preserved through all thesecuts. The tibial spine and the ACL attachment (see section C of FIG. 3A)would then be separated from the rest of the articular bone (the medialand lateral articular cartilage surfaces—see sections B and D from FIG.3A) with the bone block cutting guide 150 (FIG. 5A). The lower section160 of the bone block cutting guide will be inserted into the pre-cutsection until at least a portion of the rectangular box or cutter 170has reached the desired depth (i.e. cutting the bone block fromunderneath or inferiorly). The upper section 155 can be advanced overthe planned area on the tibia to be cut, or the tibial cut section, withthe hook placed around the ACL insertion on the tibia. The upper 155 andlower sections 160 can then be compressed together a desired amount tofacilitate removal of the bone block. The upper section may also includea surface (not shown) that pushes down on the anterior portion of thebone block, if desired. Once the bone block is cut, it can be removedfrom the cutter 170 with the ACL still attached. In various embodiments,the side and anterior walls of the cutter 170 can cut the bone blocksuch that the ACL insertion is centered in the block.

FIG. 5B depicts an additional alternative embodiment of a two-piece bonecutting guide 157 of FIG. 5A, which may include integrated or modularcomponents. The two-piece bone block cutting guide 157 may also includean upper portion 180 and a lower portion 182. The lower portion 182 mayinclude a removable arch 167, where the surgeon may desirably remove thearch 167 and replace it with a different sized arch to allow morefreedom cut a larger or smaller bone block size. The arch 167 may havevarious sharpened surfaces, such as tapered blade edges, serrated edges,compound (double) bevel, chisel, chisel with back bevel, asymmetricalsemi-convex, and/or any combinations thereof.

The upper portion 180 of the two-piece bone block cutting guide 157 mayinclude a hook 177 that will help the surgeon to center and/or displacethe ACL while cutting the bone block. The upper portion 180 and thelower portion 182 may be designed with a compression connection as shownin FIG. 5A or FIG. 5B, securing or pinning mechanisms or any othermechanism known in the art. Furthermore, the back faces 185 of the upperportion 180 and the lower portion 182 may also be designed with a backplate 190 as shown in FIG. 5D. In various designs, a back plate 190 asshown in FIG. 5D may be provided that connects to the bone blocks 180and 182 in a removable and slideable fashion, allowing the back faces185 of the bone cutting block guides to slide along the back plate 190.

FIGS. 5C and 5D depict additional alternative embodiments of two-piecebone cutting guides 197 of FIG. 5A, which may include integrated ormodular components, a compression member, pinning mechanisms, and/orremovable or slideable back plate. The two-piece bone cutting blockguides 197 may include a through-bore 195 where a screw type compressionmechanism may be inserted. The through-bore 195 will be co-aligned withthe upper portion 192 and the lower portion 193 to allow for acompression connection, where the upper 192 and lower 193 portions movetoward each other to cut bone. Alternatively, the through-bore 195 maybe designed to secure the upper 192 and/or lower 193 portions to anysurface of the tibia (i.e. the anterior or articular surface) by usingstandard OR pins—thus, preventing linear or rotational movement.

The two-piece bone cutting block guides 197 may also be equipped with aslideable and/or removable back plate 190 (as shown in FIG. 5D), wherethe back plate 190 may allow linear translation while compressing theupper 192 and lower 193 portions of the bone cutting block guides. Theback plate 190 may also serve as a positive stop on the anterior surfaceof the tibial bone, preventing the two-piece bone block cutting guide197 from sliding posteriorly during cutting.

Although, the surgeon may use the two-piece bone block cutting guide 157and 197 in a manner similar to that described in FIG. 5A, the surgeonmay adapt the modular tool to a variety of different procedures. Forexample, the arch 167 on the lower portion 182 may also be used to trapthe ACL. If desired, the surgeon may disconnect the arch 167 from thelower portion 182 to encircle or place the arch 167 around the ACL forprotection, and reconnecting the arch 167 to the lower portion 182. Oncethe ACL is trapped, the surgeon may choose to use the upper portion 180to center the ACL, and the surgeon may cut on the outside of the arch167 to remove the bone block and prevent severing of the ligament. Inaddition, the removable arch 167 may produce an enclosure or restrictedarea 172 where the surgeon may insert an osteotome, reciprocating saw,or other similar surgical tools to cut a desired or predetermined boneblock size.

FIG. 6A depicts an alternative embodiment of a bone block cutting guide200, where the tool has a superior portion 205 that cuts down on thetibial bone and cuts at least two sides of the bone block. The superiorand inferior portions are desirably connected by a compressionconnection, which in FIG. 6A is depicted as a 4-bar linkage. Theinferior portion 210 of the tool can be a comparatively thinner metalshim that slides into a horizontal proximal tibia bone cut made by thesurgeon. The inferior portion 210 may be used as a protective platewhile the surgeon is conducting the bone cut or the plate is used asleverage to provide compressive force for cutting. The inferior portion210 could slide into the standard horizontal cut (see section A in FIG.3A) that surgeons make while removing the necessary tibial bone to makeroom for the tibial component. The superior portion 205 can have asimilar hook or other feature (not shown) that can center the ACLinsertion in the bone block. The superior portion also has a pair ofvertical side walls 215 having an edged or sharpened lower surface forcutting the tibial bone as the tool 200 is advanced into the bone. Theside walls 215 may be designed with a variety of sharpened surfaces,such as tapered blade edges, serrated edges, compound (double) bevel,chisel, chisel with back bevel, asymmetrical semi-convex, and/or anycombinations thereof.

In this embodiment, the inferior portion 210 could be slid or insertedinto a previous lateral bone cut in the tibia made by the surgeon usingcommonly available saws until the surgeon reaches the desired depth. Thesuperior portion 205 with the sidewalls 215 may desirably straddle theACL insertion point. The surgeon may subsequently apply compressionbetween the superior 205 and inferior 210 portions to cut a bone blockout of the tibial bone portion.

FIG. 6B depicts an additional alternative embodiment of the bone blockcut guide of FIG. 6A. In this embodiment, the two-piece bone block cutguide 220 may have a superior 230 and inferior portion 240, athread-screw compression connection mechanism or a pinning mechanisminserted in the bore 250, and/or a guide aperture 260. A thread-screwcompression connection mechanism may be inserted in the bore 250 toallow the surgeon to fix, secure and/or stabilize the inferior 240 andsuperior 230 portions by compressing the pieces toward each other to cuta bone block. The thread-screw compression connection mechanism may alsobe used as a positive stop to prevent posterior advancement duringcutting of the bone block. The bore 250 may also be designed to allowstandard OR pins to be placed to prevent movement or rotation.Furthermore, the guide aperture 260 may also be used separately to cutto a surgeon's desired size bone block. The surgeon may use a standardsurgical saw and insert within the guide aperture 260 to cut the boneblock.

FIG. 7A shows a one-piece alternative embodiment of a bone block cuttingguide 270. The bone block cutting guide 270 may come equipped withcutting surfaces 280 and an impacting surface 310. The cutting surfaces280 may include a variety of blade shapes, such as tapered blade edges,serrated edges, compound (double) bevel, chisel, chisel with back bevel,asymmetrical semi-convex, and/or any combination thereof. The impactingsurface 310 may be used by the surgeon when the surgeon places the boneblock cutting guide 270 on the articular surface of the tibia or theanterior surface of the tibia, and the surgeon can subsequently impactthe impact surface 310 with standard available impacting tools until thesurgeon obtains the desired bone block size. The impact surface 310 maybe available in alternative shapes, such as curved, radiused, and/orconcave (not shown) to allow the ACL to fit or match within the shapedimpact surface. The bone block cutting guide 270 may be designed with avariety of bone block widths 290, heights and/or depths. The sizes maybe provided within a surgical kit should the surgeon require increasedor decreased bone block sizes.

FIGS. 7B and 7C depict exemplary embodiments of a one-piece wedge-shapedbone block cutting guide 320 and a modular wedge-shaped bone blockcutting guide 360. The wedge-shaped bone block cutting guides 320 and360 may be impacted on the handle impact surface 350 while placed on theanterior surface of the tibial bone until the surgeon reaches thedesired depth of the bone block. The surgeon may subsequently use astandard osteotomy saw to cut the remaining block from the tibia. Thewedge-shaped bone block cutting guides 320 and 360 may be designed toaccommodate various wedge shapes 340 (see FIG. 18) derived fromdimensions predetermined from preoperative images or from a standardlibrary database. Furthermore, the cutting surfaces 330 may be designedwith a variety of sharpened surfaces, or modular cutting surfaces 370.

In an alternate embodiment, a bone block cutting guide may be designedto provide a cut area that is recessed or inset 580 from the surface ofthe tibia 10 as shown in FIG. 19. The surgeon may desirably cut the boneblock away from the anterior surface 590 of the tibia for a variety ofreasons and/or purposes, such as adjustment, correction, supplementalfixation and/or to accommodate bone degradation.

In another embodiment, a bone block cutting guide may be designed toreduce and/or eliminate the potential to violate the anterior tibialcortex while cutting the bone block (not shown). The bone block could befashioned by two converging bone cuts, representing a wedge bone block560. One cut could start at the medial articular surface of the tibiaand head inferiorly and laterally. The other cut could start at thelateral articular surface of the tibia and head inferiorly and/ormedially 570 (see FIG. 18). The two cuts would intersect approximately 1cm below the articular surface. Anterior and posterior wall cuts couldbe made. The cuts could be made with an osteotome, a reciprocating saw,or any other readily available cutting tool in the OR. The bone blockforming tool may be designed as a patient specific guide or jig to helpguide all 4 cuts made to the tibia.

In an alternative embodiment, the bone block cutting guide could be a3-sided punch (inferior bone cut and 2 side walls) (not shown) that isadvanced from the anterior cortex of the tibia in a posterior direction.The 3-sided punch could also guide a reciprocating saw blade. The punchcould be inserted into the tibial bone a set distance. The posteriorwall cut could be made with an osteotome. The 3-sided punch could beguided into the correct position by a patient specific tibial jig. Thesame tibial jig could also guide the proximal tibial bone cut after thebone block was fashioned and mobilized out of the tibia.

In various embodiments, the bone block cutting guide tools may bedesigned to be integrated with various commercially available tibial andfemoral resection blocks, templates or cutting guides for furthersupport, securement, alignment, etc. In other various embodiments, thebone forming tool may be designed as adjustable to accommodate or adaptthe tool to a desired thickness of a specified bone block, or to adesired plane to cut the bone block. For example, if the overallthickness of the bone block was too thin to get adequate healing of thebone block back to the proximal tibia or risked the possibility of the abone block fracture, then the bone block could be fashioned such thatthe bone block was substantially bigger than it otherwise would havebeen if the horizontal tibial cut was made first. Any embodiment of thetool can be made adjustable, and it could fashion the bone block out ofthe proximal tibial bone before the horizontal tibial cut is made. Thehorizontal or inferior bone cut for the bone block could be made belowthe intended horizontal bone cut for the tibial implant. The bone blockcould be a thicker piece of bone in the cephalad to caudal directionthan the articular bone thickness that is removed with the horizontaltibial cut. The floor of the bone block could be below the cut surfaceof the proximal tibia so that the bone block would be substantiallythicker.

The bone block could be bi-cortical (not shown). The position of theintended bone block could be verified first with a guide wire that couldbe inserted from the ACL insertion on the tibia and directed towards theanterior tibial cortex. Alternatively, the guide wire could be startedon the anterior tibial cortex and directed toward the ACL insertion witha guide that is well known in the art. The surgeon could then slide acylindrical reamer over the guide wire and drill a cylindrical core ofbone that would include the ACL attachment on one end. The same guidewire and cylindrical reamer could also be used on the femoral side aswell to remove the ACL insertion from the femur instead of from thetibia. The cylindrical bone portions from the tibia and/or femur withACL attachment could be maneuvered into the knee joint (i.e.posteromedial, posterolateral, medially, laterally, and/or posteriorly)and out of the way. The implants could be inserted and then thecylindrical bone with ACL attachment could be repositioned back into thecylindrical hole from which it came. An interference screw or otherattachment mechanisms could fixate the cylindrical bone block back tothe native tibial or femoral bone.

The bone block could be fashioned to include both the ACL and PCLattachment on the same bone block (not shown). This bicruciate boneblock could include both the anterior and posterior cortex of theintercondylar tibial region as shown in FIG. 18. The tibial prosthesiscould then have a central opening or window to allow for reattachment ofthe bi-cruciate bone block. The tibial prosthesis might have a morerobust post and keel to compensate for the structural weakness in themiddle of the tibial component.

Tibial Prosthesis Embodiments

FIG. 8A depicts an isometric view one exemplary embodiment of a tibialprosthesis 380 for use with various embodiments previously described.The tibial prosthesis 380 may include an anterior cut-out section 390and/or a posterior cut-out section 395 that desirably facilitates thereattachment of the bone block and ACL and/or PCL insertion (not shown)to the proximal tibia. In one embodiment, the anterior cut-out 390 maybe designed to closely match, substantially match, or conform to thedesired bone block dimensions. Alternatively, the anterior cut-out 390may be designed completely open, which may allow the surgeon significantflexibility in placement and/or orientation of the bone block afterimplantation of the tibial implant has been achieved.

For example, the open anterior cut-out 390 described herein could beparticularly useful where the ACL may require adjustment, such aschanges in joint line height, coronal alignment correction, and ACLlengthening or shortening than an ACL preserving TKA by repositioning ormodifying the bone block. If the ACL were too tight, then additionalbone could be resected from the posterior side of the bone block toeffectively allow the bone block to sit more posterior on the tibia andloosen up the ACL. Conversely, if the ACL were too loose, additionalbone, polyethylene or some sort of spacer could be removed or placedbehind, on the sides, bottom and/or at an offset dimension relative tothe bone block to effectively move the bone block forward or anyrelevant direction to tighten the ACL graft. In various embodiments, ifthe bone block were cut asymmetrically, the rotation of the block todifferent orientations relative to the knee could potentially adjust thelooseness and/or tightness of the ACL in a desired manner. Additionalbone could be removed from the bone block to lower the block and tightenup the ACL graft. In various embodiments, the reattachment of the boneblock to the tibia may result in different positioning, angulation,and/or orientation of the soft tissue attachment point relative to thepreoperative positioning, angulation, and/or orientation (i.e. thedifferent position may be medial, lateral, inferior, superior, anterior,posterior, angled, and any combination thereof relative to thepreoperative position).

FIG. 8B depicts the top view of an exemplary embodiment of the tibialprosthesis 380 of FIG. 8A. The tibial prosthesis 380 may includerecessed surfaces or trays 400 where tibial inserts (not shown) may beplaced. In various embodiments, a tibial prosthesis 380 could alsoincorporate one or more locking mechanisms (not shown) to secure apolyethylene or other tibial insert into a tibial tray. In one exemplarylocking mechanism, a corresponding lower surface on the tibial insertcould engage one or more ridges on the surface 400 of the tibial tray,thereby locking the tibial insert in a desired position relative to thetray.

The tibial prosthesis 380 and the tibial inserts may be designed in avariety of sizes to accommodate patient knee anatomy. In someembodiments, the polyethylene is a one-piece polyethylene (as with mosttraditional total knee replacements). In some embodiments, thepolyethylene is a two-piece polyethylene with a separate medial andlateral polyethylene. Various embodiments of the tibial implant couldstill include a central stem and/or keel.

In other alternative embodiments, shown in FIGS. 9 and 10, a tibialprosthesis 410 and 450 could include a partially-blocked section with ananterior metal wall 420 and 460 or other feature on thepartially-blocked section, which in this embodiment resembles a hole orrestricted opening 440 in the tibial prosthesis. The anterior metal wall420 and 460 may be designed with a variety of shapes and dimensions tosubstantially match or conform to the shape of the cut bone block. Inone embodiment, the anterior metal wall 420 may be designed as anintegrated one-piece design or as a two-piece design with releasableconnection mechanisms or features. The anterior metal wall 420 mayinclude or be replaced with a large radius 430 anterior metal wall toaccommodate over-sized cut bone blocks to fit within the over-sizedrestricted opening 440. However, in one embodiment, the restrictedopening 440 may be designed to closely match, substantially match, orconform to the desired bone block dimensions.

FIG. 10 depicts a tibial prosthesis 450 with a smaller restrictedopening 440, where the anterior metal wall 460 may have a smaller radius470 design to accommodate tighter or smaller cut bone blocks to fitwithin the restricted opening 440. In one embodiment, the restrictedopening 440 may be designed with enough space to allow the surgeonsignificant flexibility in placement, orientation and/or modification ofthe bone block after implantation of the tibial implant has beenachieved to correct varus/valgus alignment, ligamenttightness/looseness, and/or other anatomical deficiencies. However, inother embodiments, the restricted opening 440 may be designed to closelymatch, substantially match, or conform to the desired bone blockdimensions. Desirably, the anterior metal wall 430 and 460 may beavailable in different shapes and sizes that could be provided in a kitfor the surgeon's convenience.

FIGS. 11A and 11B depict another alternative embodiment in various viewsof a tibial prosthesis 480 that includes a modular anterior metal wall490 that may be connected to the outside of the tibial prosthesis 480.The modular anterior metal wall 490 could be releasably connected to theouter wall of the tibial prosthesis 480 using a variety of connectionmechanisms known in the art. The modular anterior metal wall 490 may bedesigned to substantially match the thickness of the tibial prosthesis490, or at least a portion of the modular anterior wall 490 may extendonto the anterior surface of the tibia for securing the bone block inplace.

FIGS. 12A and 12B depict an alternative embodiment of a tibialprosthesis 500A that includes an anterior metal wall 510 and medialand/or lateral loops 520. In this embodiment, the tibial prosthesis 500Acould include a plurality of loops or holes (not shown) in the medialand lateral side walls of the tibial prosthesis where the bone blockwould be positioned within the restricted opening 440. The loops 520 maydesirably allow suture fixation over the bone block for further oradditional securement, provide a tightening feature, and/or providefixation to the tibial prosthesis 500A. Alternatively, the tibialprosthesis 500B may be used without the anterior metal wall 510, butretain the medial/lateral loops 520 for additional fixation of the boneblock as shown in FIGS. 14A and 14B.

Similar loops could be provided in the anterior and posterior section ofa portion of the tibial prosthesis 530, as shown in FIGS. 13A and 13B.The loops may be designed on the anterior metal wall 540 and/or theposterior/anterior wall 550 of the tibial prosthesis 530 of FIG. 13B, ifdesired. Alternatively, the loops may be placed on medial, lateral,anterior, posterior sides of the tibial prosthesis 530 or the anteriormetal wall 540, and/or any combination thereof.

In another alternative embodiment of the tibial prosthesis, the tibialprosthesis could be designed to allow fixation of the bone block to theproximal tibia, anterior surface of the tibia, and/or tibial prosthesisusing non-suture fixation (e.g., using a dove tail, polyethyleneoverhanging the bone block, screw fixation of the bone block into theproximal tibial bone, screw fixation of the bone block into the tibialcomponent, belts and/or support rails around the block, etc.—not shown).A wide variety of other fixation modalities could be used to secure thebone block to the resected tibial surface, to the tibial component,and/or to various combinations thereof. In one exemplary embodiment, thebone block could be cut into an asymmetrical or other shape, such thatthe block could be rotated to a first direction for insertion throughthe anterior cutout, but subsequent rotation or manipulation of the boneblock could wedge the bone block within the cutout and prevent egress(i.e., the bone block becomes too big to travel through the cutout inthe second orientation).

Ligament Preservation Method

One significant feature of the various embodiments described herein isthat the proposed surgical procedure does not require that a surgeonlearn a completely new procedure or become familiar with a completelynew set of implants and surgical tools to accomplish the surgicalcorrections described herein. The procedure allows the surgeon to resectthe standard portion of the proximal tibia while retaining the ACLinsertion on the tibia. This standard portion of the proximal tibia isresected regardless of whether the surgeon desires to preserve the ACLinsertion. In addition, the design changes to the tibial tray so as toaccommodate the bone block will not significantly alter the surgicalprocedure, nor will they significantly affect the strength and/orsurvival of the implant. The disclosed procedure also allows the surgeonthe ability to sublux the tibia forward to improve exposure, which istypically performed with most knee replacements.

With the various improved devices and techniques described herein, asurgeon could preserve the ACL and PCL while performing a standard ormodified improved total knee arthroplasty. The surgeon will be able torefrain from cutting the ACL insertion on the proximal tibia or damagingthe ACL insertion on the tibia in any way. After making the horizontal,proximal tibial cut with any of the proximal tibial cutting guides thatare readily used and known in the art, the surgeon can employ thevarious systems and embodiments described herein to create a bone blockwith the ACL and/or PCL insertion, include the use of any of theembodiments of bone-cutting and/or shaping tools contemplated herein.

The tibial bone block with the preserved ACL can be removed or separatedfrom the rest of the proximal tibial bone, and moved out of the way tofacilitate surgical access to the intended treatment site.Alternatively, the bone block cutting tools could be used to hold thebone block, and such tools may be designed with clips, clamps or otherfeatures that will assist the surgeon in setting the bone block asideduring surgery. By moving the mobile ACL bone block out of the way, thesurgeon is able to distract or otherwise manipulate the tibia and femurin a typical manner to allow the surgeon access to the entire tibialplateau and also the posterior knee structures. By moving the mobile ACLbone block out of the way, the surgeon can implant the tibial prosthesisperpendicular to the mechanical axis of the tibia.

For example, once separated from the tibia the mobile ACL bone blockportion can be moved into the posterior aspect of the knee while thesurgeon prepares the bone cuts on the distal femur and proximal tibia.Because the ACL and associated bone block can be treated similarly to aresected ACL, the preparation of the tibia and femur can be performedunder protocols and methods well known in the art. Similarly, the tibialand femoral components can be secured into place through techniques andprocedures used and well known in the art (e.g., cement or press fit).

After the proximal tibia and distal femur have been prepared or resectedfor their implant components, the ACL bone block can be reinserted intothe precut area on the tibia and/or attached to the tibial implant. Thebone block may be inserted before, after and/or concurrently with thevarious implant components, depending upon surgeon preference. The boneblock may be manipulated, modified, repositioned, wedged, press-fitand/or otherwise mechanically secured into the original anterior cut outof the tibial component, if desired. The various mechanical securementsmay include alternative mechanical components or mechanical featurescarved into the bone block. For example, an interference screw could bewedged between the bone block and the tibial bone to secure the boneblock to the tibial bone. The interference screw is a screw that may beindicated for fixation of soft tissue and bone-tendon-bone grafts duringcruciate ligament reconstruction of the knee. The screw may be made outof a bioabsorbable and/or biocomposite material, i.e. triCalciumphosphate, to allow absorption and enhance bone growth. Other materialsof screws may be available in other metals and polymers, such astitanium or TFE, and/or other types of fixation screws may be used.

Another example of a mechanical feature may require incorporating alocking mechanism into the bone block, into the tibial prosthesis,and/or into the tibial bone. A portion of the bone block could be shapedinto a dove tail or other arrangement such bone block can be secured tothe tibial bone and/or the tibial prosthesis. In various alternativeembodiments, the polyethylene spacer could also incorporate features tohold the bone block in place.

Alternatively, the surgeon may determine that the patient requiresalignment correction and would like to reposition the bone block to asecondary position for correction. The surgeon may desirably decide toconduct various ranges of motion of the knee to determine the propertension in both flexion and extension. This technique is similar to aprimary ACL reconstruction that is well known in the sports medicineart. Because the bone block and associated ACL should see significantloading, and the loading of the ACL tends to pull the ACL into the kneejoint, the tibial component may be pulled upwards and/or anteriorlyduring flexion and/or extension of the patient's knee.

For example, it may be advantageous for the surgeon to place orreposition the bone block to the anterior aspect of the tibia, or atleast a portion of the bone block to the anterior aspect of the tibia insome manner. Once the proper correction or tension is achieved, thesurgeon may use any of the bone block cutting guides contemplated hereinto create a secondary opening or larger opening where the bone block canbe reinserted for correction purposes, desirably restoring and/orpreserving the ACL function and alignment. The ACL bone block can bemanipulated, wedged, press-fit or otherwise mechanically secured intothe secondary anterior cut out of the tibial component, if desired.

To obtain a desired tensioning of the soft tissues including thereplaced ACL (and thereby obtain desired kinematics of the repairedjoint), the surgeon may perform additional knee balancing afterinsertion of all implant components and reattachment of the bone block,but before the insertion of one or more tibial spacers. Once desiredbalancing has been obtained, the appropriate spacer(s) may beintroduced. If proper balancing cannot be obtained, the surgeon mayelect to reorient and/or reposition the bone block as described hereinto alter the tension and/or direction of action of the ACL, andsubsequently balance the knee using appropriate spacers.

The surgeon may decide to position the tibial prosthesis on the resectedtibia after (or potentially prior to) reinsertion of the bone block. Thesurgeon may use any of the tibial prosthesis contemplated herein toaccommodate the bone block. In one embodiment, the surgeon coulddesirably use a tibial prosthesis with loops and/or anterior metal wallsto provide further securement onto the tibia (as shown in FIG. 15through 17).

Once the bone block is fastened into place and/or compressed back downon top of the tibial plateau, the surgeon may utilize standard availablesutures in the OR to thread through the loops and knot accordinglyand/or the manufacturer may decide to pre-load the sutures with thetibial prosthesis if desired. Any type of sutures may be used, such aschromic or plain catgut, polyester, polyethylene, polybutylate, nylon,polydiaoxanone (PDS), polyglactin (Vicryl), polypropylene (Prolene),polyglycolic acid (Dexon), prolene, silk, fibrous materials, metals(i.e. stainless steel), absorbable, non-absorbable, and/or anycombinations thereof. Such suture holes could be in the anterior,medial, lateral, and posterior sidewalls of the anterior cut-out and/orin the tibial component. The sutures could be passed through the ACLgraft and bone block, be passed over the bone block and around the ACL,and/or passed through the hole out of the anterior cortex on the tibiaso the surgeon could tension the bone block with the whole construct inplace. The sutures may be placed in a desired orientation based on thedesired surgeon's preference, and the design of the tibial tray. Theorientation of the sutures may be positioned in the medial-lateraldirection (as shown in FIGS. 15A, 15B, 16A and 16B) oranterior-posterior direction (as shown in FIGS. 17A and 17B), or anycombination thereof.

In various embodiments, such as where the surgeon may decide to make anadjustment, correction or alignment of the bone block using a secondaryanterior cut-out, it may be desirous in various embodiments to include asupplementary fixation feature that anchors the bone block and/or tibialcomponent to the front of the tibia as well as to the resected tibialsurface. Such attachment could include plating or screw fixation to thefront of tibial, with commensurate securement to one or both of the boneblock and/or tibial plate.

In various alternative embodiments, the techniques and system disclosedherein could be used in conjunction with surgical procedures where oneor both of the medial portion and/or lateral portion of a tibia might beremoved (if desired, using similar cutting tools and techniques). In thedisclosed embodiment, the retention of the ACL and PCL, and theassociated tension within the knee joint, substantially limits surgicalaccess to the top of the tibia. Accordingly, the cutting of a bone blockand “freeing” of the ACL in this manner might facilitate the surgeon'saccess to the tibia and femur and allow for removal of relevantstructures and preparation for the tibial tray implant. If desired,various other cutting tool arrangements, including open-faced guidetools allowing router or rongeur access to the face of the tibia toshape desired surface planes and/or structures, can be utilized.

Any material known in the art can be used for any of the implant, tools,guides and/or systems described in the foregoing embodiments, forexample including, but not limited to metal, metal alloys, combinationsof metals, plastic, polyethylene, ceramics, cross-linked polyethylene'sor polymers or plastics, and biologic materials. In addition, thebiologic materials may further include any biocompatible coatings thatmay assist with the healing response after surgery.

Any fixation techniques and combinations thereof known in the art can beused for any of the implant systems and component described in theforegoing embodiments, for example including, but not limited tocementing techniques, porous coating of at least portions of an implantcomponent, press fit techniques of at least a portion of an implant,ingrowth techniques, etc.

INCORPORATION BY REFERENCE

The entire disclosure of each of the publications, patent documents, andother references referred to herein is incorporated herein by referencein its entirety for all purposes to the same extent as if eachindividual source were individually denoted as being incorporated byreference.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. The scope of theinvention is thus intended to include all changes that come within themeaning and range of equivalency of the descriptions provided herein.

Many of the aspects and advantages of the present invention may be moreclearly understood and appreciated by reference to the accompanyingdrawings. The accompanying drawings are incorporated herein and form apart of the specification, illustrating embodiments of the presentinvention and together with the description, disclose the principles ofthe invention.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be readily apparent to those of ordinary skill inthe art in light of the teachings of this invention that certain changesand modifications may be made thereto without departing from the spiritor scope of the disclosure herein.

1. A surgical cut guide for guiding a surgical tool to resect a portionof a tibia having an at least one attached ligament, comprising: a bodyhaving a first tibial contacting surface and a second generally opposingsurface; the body including a first aperture and a second aperture, eachof the apertures extending through the body from the first tibialcontacting surface to the generally opposing second surface; the firstand second apertures being sized and configured to accommodate asurgical cutting tool for resecting the portion of the tibia; the bodyfurther including a channel extending from the first tibial contactsurface to the second surface, at least a portion of the channelpositioned between the first aperture and the second aperture; and thechannel being sized and configured to accommodate at least a portion ofthe at least one attached ligament when said first tibial contactingsurface is in a desired position relative to the tibia.
 2. The surgicalcut guide of claim 1, wherein the first and second apertures compriseelongated slots.
 3. The surgical cut guide of claim 2, wherein the firstand second apertures comprise elongated slots aligned parallel to eachother.
 4. The surgical cut guide of claim 2, wherein the first andsecond apertures comprise elongated slots that converge.
 5. A tibialimplant comprising: a platform having an upper surface and a bottomsurface, the upper surface configured to receive a tibial insert; a stemextending downwardly from the bottom surface, the bottom surfacecontacting the resected proximal tibia; and the platform having ananterior cut-out, the anterior cut-out having a wall that extendsbetween the upper surface and the bottom surface of the platform, thewall having a plurality of loops extending outwardly from the wall. 6.The tibial implant of claim 5, further comprising a posterior cut-out.7. The tibial implant of claim 5, further comprising a window.
 8. Thetibial implant of claim 5, further comprising a non-planar arm extendingfrom a medial wall of the anterior cut-out to a lateral wall of theanterior cut-out.
 9. The tibial implant of claim 8, wherein thenon-planar arm comprises a plurality of loops extending towards theanterior cut-out.
 10. The tibial implant of claim 5, wherein theanterior cut-out substantially matches a shape of a tibial bone portionhaving an at least one attached ligament.
 11. The tibial implant ofclaim 7, wherein the window substantially matches a shape of a tibialbone portion having an at least one attached ligament.
 12. The tibialimplant of claim 5, wherein the anterior cut-out comprises a connectionmechanism, the connection mechanism configured to mate with a tibialbone portion having at least one attached ligament.
 13. A method ofpreserving a cruciate ligament in a knee joint during knee arthroplasty,comprises the steps of: accessing a surface of a tibia of the knee;separating a tibial bone portion from the tibia, the tibial bone portionincluding a cruciate ligament attachment point, the cruciate ligamentextending to a femur of the knee joint; preparing the tibia to receive atibial prosthesis; implanting the tibial prosthesis on the tibia, thetibial prosthesis including an anterior portion sized and configured toaccommodate the tibial bone portion; and attaching the tibial boneportion to the tibia, whereby the cruciate ligament reconnects the femurto the tibia.
 14. The method of claim 13, wherein the step of separatinga tibial bone portion from the tibia comprises the steps of: placing atibial cutting jig on the tibia proximate to the cruciate ligamentattachment point, the tibial cutting jig including a plurality ofcutting guide surfaces separated by a channel, the channel sized andconfigured to accommodate the cruciate ligament attachment point;inserting a surgical cutting tool through the plurality of cutting guidesurfaces to cut the tibia.
 15. The method of claim 13, furthercomprising attaching the tibial bone portion to the tibial prosthesis.16. The method of claim 13, wherein the step of attaching the tibialbone portion to the tibia comprises attaching the tibial bone portion toan anterior surface of the tibia.
 17. The method of claim 13, furthercomprising positioning the tibial bone portion within the anteriorportion of the tibial prosthesis, such that at least a first surface ofthe tibial bone portion contacts the tibial prosthesis and at least asecond surface of the tibial bone portion contacts a resected surface ofthe tibia.
 18. The method of claim 13, further comprising the step ofconnecting a tibial insert to an upper surface of the tibial prosthesisafter completing the step of attaching the tibial bone portion to thetibia.
 19. The method of claim 13, wherein the step of attaching thetibial bone portion to the tibia comprises attaching the tibial boneportion to the tibia such that a resulting position of the cruciateligament attachment point is different from a preoperative position ofthe cruciate ligament attachment point.
 20. The method of claim 19,wherein the resulting position of the cruciate ligament attachment pointrelative to the preoperative position is selected from the groupconsisting of medial, lateral, inferior, superior, anterior, posterior,angled, and any combination thereof.